Pad printing devices have been in existence for a long period of time. Pad printers are typically used to transfer custom images from an ink pad to a non-planar surface. The most familiar use of pad printers is probably the printing of company names and logos on coffee cups, pens, golf balls, and the like.
Many pad printers are fully automatic, commercial printers that are capable of printing items in large volume. Commercial printers are very large machines and tend to be very expensive. At today's prices, some commercial printers cost as much as $100,000.
The expense of a commercial printer is justified for some companies. A golf ball manufacturer, for example, needs a commercial printer because it has to print its trademarks and model numbers on many thousands or millions of golf balls. Other companies do not print items at volumes that justify the expense of a commercial printer. They still have printing needs, however, which has created a market for smaller, hand-operated pad printers.
In order to avoid confusion, when the term “pad printer” is used below, it means the hand-operated kind. “Commercial printer” means the fully automated kind. However, this nomenclature is not meant to limit the scope of what is considered to be the invention. In some cases, for example, it may be possible to automate the operation of certain pad printers which are normally hand-operated. Or a pad printer may be semiautomatic in operation and still be regarded as a “pad printer” in the context of the invention described here. Consequently, the term should be taken as covering any type of pad printer whether or not it is hand-operated or fully automatic.
One of the most common hand-operated pad printers on the market today is a Japanese multi-pad printer manufactured by the Kobo Company. The Kobo printer has a hand-operated table which carries both a turntable and a print plate/ink reservoir tray (“print tray”). Moving the table back and forth respectively positions the turntable and print tray below a print pad.
The print pad is hand-operated by a spring-biased crank handle. The crank handle moves the print pad vertically up and down relative to the table.
Ink is swiped across a print plate held in the print tray as the tray is moved below the print pad. The crank arm is then pulled down, which correspondingly moves the print pad down onto the print plate, thereby causing the pad to pick up an ink image (company logo, etc.) from the print plate. Then, the crank handle is released. The spring action of the handle causes it to return to its initial position which also vertically raises the print pad relative to the table.
The table is then moved to bring the turntable directly below the print pad. The turntable carries the item (coffee mug or the like) upon which the image is to be printed. At that point, the crank arm is once again pulled down to likewise bring the print pad into contact with the item, thereby printing the image on the item's surface.
The invention disclosed here generally operates in the same way as the pad printer described above. However, the invention improves upon existing pad printers in two ways.
First, the reciprocating tables of existing pad printers are mounted to a base by means of conventional metal rollers and tracks. While this type of construction certainly works well, it is also an overdesign relative to the way the typical pad printer is used. It is also an expensive component for the pad printer manufacturer. The present invention provides an alternative to the conventional roller and track design of a pad printer table which is much cheaper to make but still provides more than adequate design tolerances for the table.
Second, the conventional pad printer requires essentially three operations relating to table movement in order to transfer the image from the print plate (apart from the upward and downward operation of the printing pad). Two of the operations involve the basic back-and-forth reciprocating movement of the table for the purpose of respectively positioning the print tray and turntable below the print pad. The third operation involves wiping excess ink from the print plate carried by the print tray as it is moved below the print pad.
In the conventional pad printer, an operator must use one hand to move the table. When the print plate is moved below the print pad, the operator must, at the same time, use his free hand to operate an ink wipe in order to remove excess ink from the print plate. This also entails a certain amount of skill to insure that the ink is wiped from the plate in proper fashion. In the present invention, this step is completely eliminated and the ink wiping operation is fully automated.